On Sat, Aug 5, 2017 at 2:23 AM, Christopher Li <sparse@xxxxxxxxxxx> wrote: > On Fri, Aug 4, 2017 at 6:26 PM, Luc Van Oostenryck > <luc.vanoostenryck@xxxxxxxxx> wrote: >> >> I have investigated a little more because even 2.1 or 1.93s seems >> too much to me. > > Thanks for looking into this. > >> The real offending, taking about 75% of CPU time, is bb_dominates() >> which while only directly called 82000 is a recursive function which >> internally is called more than 71 million of time! >> In other words, the mean recursion depth of bb_dominates() is 860, >> which means that there are chains of bb->parent as long as 860. > > Yes, that is the impression I get as well for, some where the finding > dominates is taking a lot of time. Also the result is not saved. > >> >> By restricting the bb_dominates() in CSE to a reasonable depth of 32, >> the compile time is reduced to .8s without changing a single bit in the >> resulting code. > > We can revisit this after the release. I have side project work on finding > the dominatior tree. Don't forget that asking if this node dominates this other node is not the same question as asking for the immediate dominator of a node. In other words, even with the dominator tree you will still need to do lookups in the tree. -- Luc -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
